Ryusendo Cave

Ryusendo Cave is a limestone cave in Iwaizumi Town, Shimohei District, Iwate Prefecture, reached in about 110 minutes by bus bound for Iwaizumi (Ryusendo) from the bus stop in front of JR Morioka Station. It is also known as Iwaizumi Wakikutsu. Ryusendo is one of Japan’s "Three Great Limestone Caves" and is designated as a National Natural Monument together with the bats that live inside. In addition, its underground lake water was selected in 1985 as one of Japan’s "100 Exquisite Waters." The known total cave length is 4,088 meters, with about 700 meters open to the public. Eight underground lakes have been discovered, and three of them are currently accessible to visitors. Surveys are still ongoing and many areas remain unknown, and the total length is said to possibly exceed 5,000 meters. The highlight is the series of stalactites and stalagmites inside the cave and the vividly blue underground lake, famous for its world-class clarity. There is a best season to see the lake at its most beautiful, and it is said to be winter. Because there is little rainfall in winter and water volume stays stable, the cloudiness that can occur in other seasons is reduced. With the ground frozen, fewer droplets fall from above, so surface ripples calm down, transparency increases, and you can fully enjoy the striking blue underground lake.